High adhesion acrylate coatings f0r a photochromic ophthalmic lens

ABSTRACT

A method and coating used to prepare a photochromically-enabled bifocal ophthalmic lens. The coating is a high adhesive strength acrylate-based coating that contains a small quantity of a polycarbonate-based TPU. The coating is applied to produce an intermediate imbibable bifocal surface. A photochromic solution is subsequently imbibed by contact with the bifocal surface.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a high adhesive strength acrylate-based coatingthat contains a small quantity of a polycarbonate-based TPU. Moreparticularly, the coating is applied to produce an intermediateimbibable bifocal surface that is subsequently contacted with aphotochromic solution.

2. Description of the Related Art

In-situ coating via direct injection, so called in-mold coating, hasbeen successfully used in other industries such as automotive,construction, office products and outdoor equipment industries. It wasoriginally developed to improve the surface appearance of sheet moldingcompound (SMC) parts molded by compression molding. In more recent yearsit's been applied to injection molded thermoplastic parts.

U.S. Patent Application Publication 2003/0227109 refers to a process forcompressive decoration molding applied to the exterior of an injectionmolded box. The resulting decorative film is a coating along the top andsides of the box, that is, on surfaces perpendicular to the mold partingline. The high viscosity opaque coating is compressed at a controlledrate to provide uniform thickness on all part surfaces. The publicationis directed to solving a problem of specific product configuration anddoes not relate to forming ophthalmic lenses which require opticalclarity and varying thickness.

U.S. Patent Application Publication 2006/0151911 describes an injectionmolded part that is coated with a lacquer layer. The lacquer is injectedunder pressure into a closed mold that is treated with a mold releaseagent. Solvent free lacquers with short shelf lives are prescribedthrough implementation of a reaction injection molding (RIM) process.The injected lacquer is cured at an elevated pressure, whereby thecoating expands and then shrinks, making it difficult to control finalcoating thickness.

U.S. Patent Application Publication 2005/0089630 describes a lens madeby a first process which is then gasketed to receive a surface castlayer. The original lens must be cleaned and dried in order to apply atie coating before gasketing. The tie coating is also subject to apre-cure to partially polymerize the coating to improve its ability totie the original lens to the cast layer. The described compositions andmethods suffer from complexity and too many steps.

U.S. Patent Application Publication 2006/0118999 describes asimultaneous molding/overmolding technique utilizing a reversiblyengageable rotatable core having identical molds on multiple sides. Thetechnique is designed to allow the molding process to occur on one coreside at the same time as the overmolding process takes place on anothercore side. The parallel molds are not well suited for producing articlesof optical quality because the hardware configuration does not allow forinterchangeable mold inserts that are needed to produce lenses havingdifferent base curves. In addition, since one clamp is used to closeboth parallel molds, there is only a single clamp force profile whichrepresents a compromise between the two distinct types of moldingoperations.

U.S. Pat. No. 7,077,985 describes a film insert molding process foradding photochromic or polarizing functionality to an injection moldedlens. The functional film is sandwiched between two protective polymericlayers and pre-shaped before being placed into the bifocal injectionmold cavity. The preparation of the film involves multiple steps andrequires additional resources to keep the film inventory clean prior touse. U.S. Pat. No. 6,367,930 describes a separately preparedphotochromic TPU film and a polycarbonate ply that are collectivelyinserted into a mold for a film insert process. In an alternateembodiment, a photochromic TPU that is injected, for example via twoinjection molding machines or a two-shot injection molding machine. Inthese processes, an intermediate imbibable bifocal lens is not prepared.

This closed mold method of in-mold coating has an advantage, in that thecoating is able to cure at the same time as the part is cooling. Sinceaccess to the part is limited by the closed mold, all of these systemsintroduce the coating at the top of the mold cavity with the coatinginjector being located near the parting line. The preferred moldingmachine configurations having a vertical parting line, with the movablemold half being reciprocated in a horizontal direction. An example ofsuch machine configuration can be readily seen in U.S. Pat. No.6,180,043. This patent is concerned with high gloss, opaque coatings,containing as much as 30% and up to 45% titanium dioxide and otherpigments. Clearly, for such coatings in which one sees only a highlyreflective outer surface, there is no requirement for uniformity ortransparency, as with an optical coating. In addition, mold cleanlinessand contamination are not issues due to the higher viscosity ofpigmented coatings. U.S. Pat. No. 6,180,043 utilizes multistagedeclining clamping force during the coating cure stage, while WO2003/031138 utilizes multistage declining clamping force during theplastic injection stage.

The remaining closed mold patents describe various molding machinemodifications to contain the coating within the mold cavity. U.S. Pat.No. 6,676,877 provides a coating containment shroud along the runnerpassageway to prevent coating solution from contaminating the liquidresin in the screw. The International Publication WO 2004/048068 relatesto retrofitting existing molds for use with an in-mold coating system.Published U.S. Patent Application 2003/0077425, Published U.S. PatentApplication 2003/0082344 (corresponding to International Publication WO2003/035354), and Published U.S. Patent Application 2003/0099809 allrelate to the addition of a rim feature on the molded item, to seal theparting line and prevent coating solution leakage. While these solutionsare adequate for center-gated molds and automobile parts, they areunsuitable for the use in edge-gated molds or the product configurationof optical lenses.

U.S. Pat. No. 5,943,957 discloses a method for pad printing inked imagesonto injection-molded pieces while they are still in the mold. Thepatented method relates to conventional ink that air dries, and does notinvolve an optical grade coating that will be spread over the lens byre-clamping the mold inserts and allowing the coating to cure via theretained heat in the mold block. Published U.S. Patent Application2003/0152693 discloses pad printing of lenses, but applies a UV ormicrowave curable coating on cast lenses which are totally divorced fromany mold contact.

The present invention describes equipment and provides methods andformulation to apply a coating or thicker layer on the surface of anophthalmic lens while it is still in the mold. The coating is thermallycured by the heat from the mold and the residual heat from thethermoplastic lens to provide an imbibable bifocal surface. In order toaddress adhesion and performance defects, the formulations of theinvention include fractional amounts of a TPU in an acrylate-basedthermoset formulation.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an in-mold coatingprocess that produces an imbibable segmented optical lens.

It is a further object to specify a TPU component to the coatingformulation to enhance adhesion and offer good photochromic performance.

These and other related objects are achieved by an embodiment of theinvention which includes a method for forming a photochromically-enabledbifocal ophthalmic lens by incorporating a thermoplastic polyurethane(TPU) therein. Initially, molten thermoplastic polycarbonate (PC) resinis injected into an edge-gated cavity of an injection molding machinehaving a vertical equipment axis to provide a lens substrate. Anacrylate-based coating composition is applied onto the lens substratewhich cures to form an imbibable bifocal surface. In a subsequentoperation, a photochromic dye solution is imbibed into the surface. Theacrylate-based composition contains an adhesion enhancer comprising aTPU so that coating-to-substrate integrity is maintained following saidimbibing step.

The injecting step provides a single vision (SV) lens substrate, and theapplying step involves overmolding. The applying step includesdepositing an unpressurized full metered charge of the composition on tothe upwardly-facing convex surface of the lens substrate, and thenclamping down an upper mold half to form a bifocal lens cavity.Alternatively, the injecting step provides a bifocal lens substrate.

The coating composition includes at least 90% by weight of a blendacrylate-based thermoset materials, and less than 5 phm TPU (parts perhundred parts of monomers), and preferably less than 2 phm. For theimbibable version, the coating may comprise at least one dye selectedfrom regular dye, photochromic dye, dichroic dye or combination thereof,or the coating composition is devoid of any dyes. The TPU is apolycarbonate-based TPU, for example an aliphatic polycarbonate-basedTPU. The resulting photochromically-enabled bifocal ophtalmic lens mayhave an % T initial above 80 a % T dark around 20. The coatingcomposition is formulated by dissolving a metal salt and the TPU in asolvent blend including (1) a monofunctional (meth)acrylate; (2) amultifunctional (meth)acrylate; (3) a difunctional (meth)acrylate; (4)an aliphatic urethane diacrylate; and adding an initiator. The coatingcomposition may optionally comprise a dye which is selected from regulardye, photochromic dye, dichroic dye and combination thereof. This optionprovides the availability to modify and adjust the final tint of thelens manufactured by this process.

According to the invention, a composition is described as an imbibablethermoset composition. By imbibable, it is understood that thecomposition may be subject, after a thermal curing step according to themethod of the invention, to an imbibing process without formation ofdefects onto the lens and the coating itself. Then it may be understoodthat an imbibable composition may be clear, or comprise at least onedye. If said imbibable composition comprises dye, then it is possible ifneeded to subject the lens obtained after the curing step to an imbibingstep to obtain, for example, a lens with a low level of transmission(darkener) and/or to modify the tint. Then the composition of theinvention is a thermoset composition having (1) at least onemonofunctional (meth)acrylate; (2) at least one multifunctional(meth)acrylate; (3) at least one difunctional (meth)acrylate; (4) atleast one aliphatic urethane diacrylate; (5) at least one metal salt;(6) at least one initiator; and (7) at least one thermoplasticpolyurethane (TPU). As mentioned above, the thermoset composition mayfurther comprise one dye selected from regular dye, photochromic dye,dichroic dye and a combination thereof.

The monofunctional (meth)acrylate may be isobornyl acrylate, methylmethacrylate, benzyl methacrylate, benzyl acrylate hydroxypropylmethacrylate, 2-phenoxyethyl methacrylate, or combinations thereof. Themonofunctional (meth)acrylate is benzyl acrylate, for example.

The multifunctional (meth)acrylate may be dipentaerythritolhexaacrylate, dipentaerythritol pentaacrylate, and hexafunctionalaliphatic urethane acrylate, or combinations thereof. Themultifunctional (meth)acrylate is dipentaerythitol pentaacrylate, forexample.

The difunctional (meth)acrylate may be 1,6-hexanediol diacrylate,ethoxylated bisphenol A di(meth)acrylate, polyethylene glycoldi(meth)acrylate or combinations thereof. The metal salt is cobaltnaphthenate, for example. The initiator is tert-butylperoxybenzoate, forexample.

The thermoplastic polyurethane includes a polycarbonate-based aliphaticpolyurethane having a Specific gravity of between 1.0 and 1.3; aFlexural modulus between 550 and of 690 psi; an Ultimate Tensile ofbetween 4,000 and 6,000 psi; and Mold shrinkage of 0.006-0.014 in/in.

The monofunctional (meth)acrylate is present in an amount of about 5% to40% by weight, preferably 10 to 20%. The multifunctional (meth)acrylateis present in an amount of about 5% to 50% by weight, preferably 10 to35%. The difunctional meth(acrylate) is present in an amount of about 5%to 50% by weight, preferably 10 to 35%. The aliphatic urethanediacrylate is present in an amount of about 5% to 60% by weight,preferably 30 to 50%. The metal salt is present in an amount about 0.05to 2.0 phm, preferably about 0.25 phm. The initiator is present in anamount of about 0.1 to 5.0 phm, preferably about 1.5 phm. Thethermoplastic polyurethane (TPU) is present in an amount of about 0.5phm to 5.0 phm, preferably about 1.0 phm. The composition may furthercomprise at least one dye being present in an amount comprised from 0.1%to 5.0% by weight.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages, nature, and various additional features of the inventionwill appear more fully upon consideration of the illustrativeembodiments now to be described in detail in connection withaccompanying drawings. In the drawings:

The FIG. 1 is a flowchart outlining the steps for applying anacrylate-based coating to manufacture an imbibable surface that istreated to create a photochromic lens.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides methods and coatings used to prepare aphotochromically-enabled segmented ophthalmic lens. The coating is ahigh adhesive strength acrylate-based coating that contains a smallquantity of a polycarbonate-based TPU. The coating is applied to producean intermediate imbibable bifocal or trifocal surface. A photochromicsolution is subsequently imbibed by contact with the segmented surface.

Currently, when manufacturing photochromic polycarbonate bifocalsegmented spectacle lenses, a viscous photochromic coating is depositedonto the segmented surface. The surface discontinuity causes the coatingto build-up at the segment. When dried, such a lens has an excessiveamount of photochromic dye present at the segment. During use insunlight, UV radiation causes an undesirable darker color at thesegment.

One proposed solution involves an in-mold application of an imbibablecoating on to the bifocal surface. The coating has a favorable uniformthickness which would be well suited for imbibing with a photochromicdye solution. Unfortunately, the solution has the effect ofdeteriorating the coating, and such photochromically dyed coatingsroutinely fail basic adhesion tests.

Aside from film insert molding techniques, attempts have been made toincorporate the photochromic dye into the coating for in-moldapplication. However, the photochromic dye molecules are unstable athigh temperatures, and therefore this approach limits the parameters forprocessing high temperature resins. In addition, the coating layerdepth, and hence the dye gradient, cannot be effectively controlled orvaried.

Surprisingly, it was discovered that an imbibable coating layer could beapplied with an in-mold technique, and could be engineered to providehigh adhesion strength by adding a fractional percentage of TPU. Theimbibable coating layer is applied via an in-mold process, which will befurther explained with reference to the FIG. 1.

Beginning in step 10, there is provided an edge-gated lens mold. Themold is oriented to a vertical equipment axis. The stationary moldsection is designated as the lower convex mold half. The movable moldsection is designated as the upper concave mold half. The upper movablemold half is vertically, and reciprocally translated by a multi-tonclamping unit, for example a clamping unit on the order of 100 tons. Instep 20, we injection mold a lens substrate. A molten thermoplasticpolycarbonate (PC) resin is injected into the cavity at typicalpressures and temperatures in the range of 300-400 degrees Fahrenheit.

In step 30, the mold is opened with the convex surface of the lenssubstrate facing up. The mold is opened at a time when the resin issufficiently solidified to resist deformation. In step 40 anacrylate-based coating is applied to the substrate. The coating is athermoset resin containing a fractional amount of a polycarbonate-basedthermoplastic polyurethane (TPU). An unpressurized full metered chargeof coating is applied in step 40. The mold is closed in step 50 tospread the coating across the substrate surface. The same clamp forcefrom step 20 may be employed. Alternately, a reduced clamp force may beemployed. The same [bifocal] mold halves from step 20 may be employed,in which case the coating will occupy a thin volume of space created byshrinkage of the PC resin. If a single vision [SV] mold set is used instep 20, the top mold half will be swapped out and substituted with abifocal upper mold, having a base curve similar to the SV mold set.

In either case, in step 60 the coating thermally cures to form animbibable segmented lens surface. Residual heat from the lens substrateor the mold surfaces drives the thermal cure process. The lens may be abifocal type or a trifocal type. In step 70 the mold is opened and thelens is removed. The coated lens will be removed at a time when thecoating has sufficiently cured to resist deformation. In step 80, theimbibable segmented lens surface is contacted with a photochromic [Ph]solution. This step involves the introduction of heat according to apredetermined profile. In step 90 the solvent from the Ph solution isallowed to evaporate. This drying step may also involve the introductionof heat. The resulting product is a photochromically enabled segmented[bifocal or trifocal] lens featuring a high adhesion strength coating.The lens has good photochromic performance. Experiments and test resultswhich quantify the adhesion strength and photochromic performance arepresented below.

The examples and tests are presented in three sections, namely, I.Coatings which fail adhesion, II. Coatings which pass adhesion, but failphotochromic performance, and III. Coatings which pass adhesion andphotochromic performance.

Coating adhesion performance was tested by a cross-hatch adhesiontechnique where a parallel evenly spaced series of sharp razor bladesare run across the coating and then run across the coating again at a90° angle. Tape is applied and pulled and the coating is examined to seeif the coating remains on the lens or has been removed. This is known asAdhesion-Dry. The coated lens was then placed into boiling water oraqueous red dye solution and tested again, which is called Adhesion-Wet.Initially, the un-imbibed lenses were tested for Adhesion-Dry. If theysurvived they were tested for Adhesion-Wet. If the coating was stillintact they were imbibed with a photochromic solution and tested forphotochromic performance. After that, they were tested for Adhesion-Dry.If the coating was still intact the lens was tested for Adhesion-Wet.

I. First Example Set

A standard coating formulation example 1 is described below in Table 1.Cobalt naphthenate was carefully weighed out into a vial. The SR506 wasthen added which is primarily used to dissolve the cobalt naphthenateand control viscosity. The vial was lightly heated and gently swirled todissolve the cobalt napthenate quickly. CD542 was added then SR399 wasadded and mixed thoroughly. CN965 was then added and mixed untildissolved. The organic peroxide Luperox P was added last and mixed well.The solution was degassed using a vacuum pump.

Example 2 is the same as example 1 except that SR506 was replaced bySR340 and CD542 was replaced by SR603. SR340 does not dissolve cobaltnaphthenate very well.

Both example fail adhesion after imbibing with photochromics however,the photochromic performance is good.

TABLE 1 Adhesion Performance Sample 1 2 cobalt naphthenate (phm)  0.25 0.25 SR506: isobornyl acrylate (%) 20 — SR340:2-phenoxyethylmethacrylate (%) — 20 CD542: BPA (8EO) DMA (%) 30 — SR603:PEG (400) DMA (%) — 30 SR399: dipentaerythritol pentaacrylate (%) 20 20CN965: Urethane diacrylate (%) 30 30 Luperox P: t-butylperoxybenzoate(phm)  1.5  1.5 Adhesion without imbibing photochromics Dry PASS PASSWet PASS PASS Adhesion after imbibing photochromics Dry PASS PASS Wetfail fail Photochromic Performance % T initial 83.0 83.9 % T dark 22.019.8

Cobalt Naphthenate may be obtained from Sigma-Aldrich located in St.Louis, Mo. It has CAS No. 61789-51-3 and contains up to 10% cobalt, CASNo. 7440-84-4. It is also referred to as Naftolite.

SR-506 is the trade name for isobornyl acrylate available from SartomerCompany, Inc. of Exton, Pa. It has the following molecular diagram

Some of its properties are as follows: Functionality of 1, Inhibitor of170 MEHQ ppm; Water of 0.05% wt.; Acid of 0.1% wt.; Color of 20 APHA;Specific gravity of 0.987 @ 25 degrees Celsius, Viscosity of 9 cps @ 25degrees Celsius; Refractive Index of 1.4738; Surface tension of 31.7dynes/cm; a Glass transition (T_(g)) temperature of 88 degrees Celsius;Boiling Point of 120 degrees Celsius @ 15 mm; Flash Point of 106 degreesCelsius; and a Molecular Weight of 208.

SR-340 is the trade name for 2-phenoxyethyl methacrylate, a lowvolatility monofunctional, aromatic monomer offering good adhesionproperties, available from Sartomer Company, Inc. of Exton, Pa. It'smolecular diagram is represented as follows:

Some of its properties are as follows: Functionality of 1, Inhibitor or125 HQ ppm; Solvent of 0.1% wt.; Water of 0.2% wt.; Acid of 0.1% wt.;Color of 40 APHA; Specific gravity of 1.079 @ 25 degrees C.; Viscosityof 10 cps at 25 degrees C.; Refractive Index of 1.5109; Surface Tensionof 38.2 dynes/cm.; Glass Transition (T_(g)) temperature, of 54 degreesC.; Molecular Weight of 206, and a Boiling point of 260 degrees C. @ 760mm.

CD-542 is the trade name of an ethoxylated (8) bisphenol Adimethacrylate available from Sartomer Company, Inc. of Exton, Pa. Ithas the following molecular diagram

It is a low volatility monomer used in free radical polymerization. Itprovides a good hydrophobic and hydrophilic balance. It has ahydrophobic backbone for alkali solubility. Some of its properties areas follows: Functionality of 2, Inhibitor of 175 MEHQ ppm; Solvent of0.1% wt.; Water of 0.2% wt.; Acid of 0.1% wt.; Color of 40 APHA;Specific gravity of 1.119 @ 25 degrees C.; Viscosity of 420 cps at 25degrees C.; Refractive Index of 1.5147; and a Molecular Weight of 728.

SR-603 is the trade name for polyethylene glycol (400) dimethacrylateavailable from Sartomer Company, Inc. of Exton, Pa. It has the followingmolecular diagram

It is a difunctional monomer. Some of its properties are as follows:Functionality of 2, Inhibitor of 245 MEHQ ppm; Solvent of 0.1% wt.;Water of 0.4% Wt.; Acid of 0.05% wt.; Color of 100 APHA; Specificgravity of 1.117 @ 25 degrees C.; Viscosity of 85 cps at 25 degrees C.;Refractive Index of 1.4645; Surface tension of 40.0 dynes/cm; a Glasstransition (T_(g)) temperature of −21 degrees C.; and a Molecular Weightof 598.

SR-399 is the trade name for dipentaerythritol pentaacrylate availablefrom Sartomer Company, Inc. of Exton, Pa. It's molecular diagram isrepresented as follows:

Some of its properties are as follows: Functionality of 5, Inhibitor of270 MEHQ ppm; Solvent of 0.1% wt.; Water of 0.1% wt.; Acid of 0.1% wt.;Color of 50 APHA; Specific gravity of 1.192 @ 25 degrees C.; Viscosityof 13,600 cps at 25 degrees C.; Refractive Index of 1.4885; SurfaceTension of 39.9 dynes/cm.; Glass Transition Temperature, T_(g) of 90degrees C.; and a Molecular Weight of 525.

CN-965 is the trade name of an aliphatic polyester based urethanediacrylate oligomer. It is a flexible oligomer available from SartomerCompany, Inc. located in Exton, Pa. Some of its properties are: Color,APHA of 50; Density of 9.144 lbs./gal.; Elongation of 57; Functionalityof 2; Modulus of 3040 psi @ 1%; Refractive index 25′ of 1.4802; GlassTransition (Tg) temperature of −37 degrees C.; and a Viscosity of 9975cps @ 60 degrees C. It exhibits good adhesion, good chemical resistance,good heat resistance, good water resistance, good weatherability, highabrasion resistance, high flexibility, high impact strength and lowshrinkage.

Luperox P is the trade name for tert-butyl peroxybenzoate, 98% availablefrom Sigma-Aldrich of St. Louis, Mo. It has CAS No. 614-45-9 and theformula C₁₁H₁₄O₃. It is also referred to as t-butyl perbenzoate, t-butylperoxy benzoate, Esperox 10, Novox, Trigonox C, and tert-butylperbenzoate. Some of its properties are as follows: Molecular weight of194.23 AMU; BP/BP range of 75.0-76.0 degrees C. at 0.2 mmHg; Vaporpressure of 3.36 mmHg at 50 degrees C.; Vapor Density of 6.7 g/l;SG/Density of 1.034 g/cm³; Volatility of 100%; Flash point of 93 degreesC.; and a Refractive Index of 1.496.

Example 3 is the same as 2 except that SR506 was replaced by CN146 whichis described as an adhesion promoter. CN146 dissolve the cobaltnaphthenate very quickly. Again in Table 2 below, 3 fails adhesion afterimbibing but has good photochromic performances.

TABLE 2 Adhesion Performance Sample 3 cobalt naphthenate (phm)  0.25CN146: acrylic oligomer (%) 20 SR603: PEG (400) DMA (%) 30 SR399:dipentaerythritol pentaacrylate (%) 20 CN965: Urethane diacrylate (%) 30Luperox P: t-butylperoxybenzoate (phm)  1.5 Adhesion without imbibingphotochromics Dry PASS Wet PASS Adhesion after imbibing photochromicsDry PASS Wet fail Photochromic Performance % T initial 82.1 % T dark20.2

CN-146 is the trade name of an acrylic oligomer. It is an adhesiveoligomer available from Sartomer Company, Inc. located in Exton, Pa.Some of its properties are: Appearance of a clear liquid @ 20 degreesCelsius; Specific gravity of 1.26 @ 25 degrees Celsius; and a Viscosityof 3600 cps @ 25 degrees Celsius. It exhibits good adhesion to metal andplastics, low viscosity and is soluble in caustic solutions.

Polar monomers are known to enhance adhesion. Examples 4 containing HEMA(hydroxyl groups) and 5 containing acrylic acid (acid groups). Both HEMAand MMA/AA dissolve the cobalt naphthenate very quickly. Both fail dryadhesion after imbibing as shown in Table 3 below but have goodphotochromic performance.

TABLE 3 Adhesion Performance Sample 4 5 cobalt naphthenate (phm)  0.25 0.25 MMA: methylmethacrylate (%) — 10 HEMA: 2-hydroxyethylmethacrylate(%) 20 — AA: acrylic acid (%) — 10 SR603: PEG (400) DMA (%) 30 30 SR399:dipentaerythritol pentaacrylate (%) 20 20 CN965: Urethane diacrylate (%)30 30 Luperox P: t-butylperoxybenzoate (phm)  1.5  1.5 Adhesion withoutimbibing photochromics Dry PASS PASS Wet PASS PASS Adhesion afterimbibing photochromics Dry fail fail Wet na na Photochromic Performance% T initial 84.1 83.6 % T dark 21.9 20.9

II. Second Example Set

Examples 6, 7 and 8 are the same as example 1 except that CN965 has beenreplaced by the appropriate Ebecryl monomer shown in Table 4.

While 6 and 7 both pass adhesion after imbibing as shown in Table 4below, the photochromic performance is unacceptable with 6 onlydarkening to 47% T. Example 8 does not even imbibe or darken.

TABLE 4 Adhesion Performance Sample 6 7 8 cobalt naphthenate (phm)  0.25 0.25  0.25 SR506: isobornyl acrylate (%) 20 20 20 CD542: BPA (8EO) DMA(%) 30 30 30 SR399: dipentaerythritol pentaacrylate (%) 20 20 20 Ebecryl284N: Urethane diacrylate (%) 30 — — Ebecryl 1290: Urethane hexaacrylate(%) — 30 — Ebecryl 8411: Urethane diacrylate (%) — — 30 Luperox P:t-butylperoxybenzoate (phm)  1.5  1.5  1.5 Adhesion without imbibingphotochromics Dry PASS PASS PASS Wet PASS PASS PASS Adhesion afterimbibing photochromics Dry PASS PASS fail Wet PASS PASS na PhotochromicPerformance % T initial 85.2 88.0 81.2 % T dark 47.0 none 20.2

This II. Second Example Set and Table 4 indicates that routineexperimentation has some limited effect in improving either adhesion orphotochromic performance, but not both. These trials were expanded toblend in other polymers like PMMA, PVA and CAB, but similar poor resultswere obtained.

Ebecryl® 284-N is the trade name for an aliphatic urethane diacrylatediluted 12% by weight with the reactive diluent 1,6-hexanedioldiacrylate (HDODA). Ebecryl 284-N and HDODA are available from CytecSurface Specialties, Inc. of Smyrna, Ga. HDODA is also referred to ashexamethylene diacrylate having CAS No. 13048-33-4. Some of itsproperties are: Color, Gardner scale, max. of 2; Viscosity of1,900-2,300 cP at 60 degrees C.; a % NCO, max. of 0.2; Density of 1.18g/ml at 25 degrees C.; Functionality of 2 (a theoretical determinationbased on the undiluted oligomer); Oligomer of 12% by weight; Tensilestrength of 5,900 psi; Elongation at break of 58%; Boiling point of >100degrees C.; Vapor pressure of <0.01 h Pa @ 20 degrees C.; and a GlassTransition temperature of 50 degrees C.

Ebecryl® 1290 is the trade name for a hexafunctional aliphatic urethaneacrylate that exhibits very fast cure response when exposed toultraviolet light (UV) or electron beam (EB). The product is made fromacrylated aliphatic urethane in a range of 50 to 60% combined withacrylated polyol in a range of 40 to 50% by weight. Ebecryl® 1290 isavailable from Cytec Surface Specialties, Inc. of Smyrna, Ga. Some ofits properties are: Color, Gardner scale, max. of 1; Viscosity of1,800-2,200 cP at 60 degrees C.; Density 1.19 g/ml at 25 degrees C.;Functionality of 6 (a theoretical determination based on the undilutedoligomer); Tensile strength of 6,700 psi; Elongation at break of 2%;Boiling point of >100 degrees C.; Vapor pressure of <0.013 h Pa @ 20degrees C.; and a Glass Transition temperature of 69 degrees C.

Ebecryl® 8411 is the trade name for an aliphatic urethane diacrylate(aka acrylated urethane) diluted 20% by weight with the reactive diluentisobornyl acrylate (IBOA). Ebecryl 8411 and IBOA are available fromCytec Surface Specialties, Inc. of Smyrna, Ga. IBOA has CAS NO.5888-33-5. Some of the properties of Ebecryl 8411 are: Color, Gardnerscale, max. of 1; Viscosity of 3,400-9,500 cP at 65.5 degrees C.; a %NCO, max. of 0.2; Density of 1.13 g/ml at 25 degrees C.; Functionalityof 2 (a theoretical determination based on the undiluted oligomer);Oligomer of 80% by weight; Tensile strength of 1,170 psi; Elongation atbreak of 320%; Young's modulus of 1,280 psi; Boiling point of >100degrees C.; Vapor pressure of <0.013 h Pa @ 20 degrees C.; and a GlassTransition temperature of −18 degrees C.

III. Third Example Set

We now look at the examples of the invention. Example 9 containsCarbothane 3575A aliphatic polycarbonate-based TPU from Estane. Cobaltnaphthenate was carefully weighed out into a vial. MMA was then addedand the vial was gently swirled to dissolve the cobalt napthenate.Carbothane 3575A was added and the solution was heated to ˜50 C andstirred until dissolved. MMA is an excellent solvent for both the cobaltnaphthenate and Carbothane 3575A. SR603 then SR399 were added and mixedthoroughly. CN965 was then added and mixed until well mixed. The organicperoxide Luperox P was added last. Example 10 is a repeat example of 9.Example 11 is a comparative example which does not contain anyCarbothane 3575A. Table 5 below shows examples 9 and 10, both containingthe Carbothane 3575A, display excellent adhesion after imbibing withphotochromics. Also, adhesion is preserved even after 200 hours ofSunTest exposure. Additionally, the photochromic performance iscomparable to the comparative example which does not contain Carbothane3575A. Example 11 comparative example fails adhesion after imbibing butshows good photochromic performance.

TABLE 5 Adhesion Performance of the Invention Sample 11 9 10 cobaltnaphthenate (phm)  0.25  0.25  0.25 MMA: methylmethacrylate (%) 20 20 20Carbothane 3575A (phm) —  1.0  1.0 SR603: PEG (400) DMA (%) 30 30 30SR399: dipentaerythritol pentaacrylate (%) 20 20 20 CN965: Urethanediacrylate (%) 30 30 30 Luperox P: t-butylperoxybenzoate (phm)  1.5  1.5 1.5 Adhesion without imbibing photochromics Dry PASS PASS PASS Wet PASSPASS PASS Adhesion after imbibing photochromics Dry fail PASS PASS Wetna PASS PASS Photochromic Performance % T initial 82.7 83.0 83.6 % Tdark 21.1 20.5 20.4

Carbothane® is the trade name for a family of aliphatic,polycarbonate-based TPUs available from the Estane® line of LubrizolCorporation of Cleveland, Ohio. The family is characterized by excellentoxidative stability and chemical stability. Some of the properties ofCarbothane PC-3575A are: Durometer 73A Shore Hardness; Specific gravityof 1.15; Flexural modulus of 620 psi; Ultimate Tensile of 5,300 psi;Ultimate elongation of 470 psi; Tensile of psi at 100% elongation;Tensile of 500 at 200% elongation; Tensile of 900 at 300% elongation;and Mold shrinkage of 0.008-0.012 in/in.

We now look at yet another example of this invention. Example 12 is thesame as 9 except that BzA (Tg=6° C.) replaced MMA. The benzyl acrylateis an good solvent for the cobalt naphthenate and the Carbothane 3575A.Table 6 below shows 12 to have excellent adhesion. Also, adhesion ispreserved even after 200 hours of SunTest exposure. We also see animprovement in the photochromic performance with darkening at 18.4% T.Example 13 comparative example without Carbothane 3575A fails adhesionafter imbibing.

TABLE 6 Adhesion Performance of the Invention Sample 13 12 cobaltnaphthenate (phm)  0.25  0.25 BzA: benzyl acrylate (%) 20 20 Carbothane3575A (phm) —  1.0 SR603: PEG (400) DMA (%) 30 30 SR399:dipentaerythritol pentaacrylate (%) 20 20 CN965: Urethane diacrylate (%)30 30 Luperox P: t-butylperoxybenzoate (phm)  1.5  1.5 Adhesion withoutimbibing photochromics Dry PASS PASS Wet PASS PASS Adhesion afterimbibing photochromics Dry fail PASS Wet na PASS PhotochromicPerformance % T initial 81.2 82.6 % T dark 18.6 18.4

Yet another example of this invention, example 14 the same as 9 exceptthat BzMA (Tg=54° C.) replaced MMA. The benzyl methacrylate is an goodsolvent for the cobalt naphthenate and the Carbothane 3575A. Table 7below shows 14 to have excellent adhesion after imbibing. Also, adhesionis preserved even after 200 hours of SunTest exposure. The comparativeexample 15 fails adhesion after being imbibed with photochromics.

TABLE 7 Adhesion Performance of the Invention Sample 15 14 cobaltnaphthenate (phm)  0.25  0.25 BzMA: Benzyl methacrylate (%) 20 20Carbothane 3575A (phm) —  1.0 SR603: PEG (400) DMA (%) 30 30 SR399:dipentaerythritol pentaacrylate (%) 20 20 CN965: Urethane diacrylate (%)30 30 Luperox P: t-butylperoxybenzoate (phm)  1.5  1.5 Adhesion withoutimbibing photochromics Dry PASS PASS Wet PASS PASS Adhesion afterimbibing photochromics Dry fail PASS Wet na PASS PhotochromicPerformance % T initial 80.8 83.8 % T dark na 21.1

As can be seen, the TPU is effective in enhancing coating adhesion andresults in good photochromic performance. It is shown to be compatiblewith MMa, BzA, and BzMA blends of acrylate monomers. The acrylatecomponents can be present is varying amounts to provide flexibility inmaterial selection, while maintaining performance and optical quality.The imbibable segmented lens can be treated with a variety ofphotochromic dyes, for example, naphthopyrans, fulgides, benzopyrans,fulgimides, spironaphthopyrans, spirobenzoxazines, spironaphthoxazines,spirobenzopyrans, and combinations. The dyes can be blended to achievedifferent performance or cosmetic characteristics.

Having described preferred embodiments for lens manufacturing, materialsused therein and methods for processing the same (which are intended tobe illustrative and not limiting), it is noted that modifications andvariations can be made by persons skilled in the art in light of theabove teachings. It is therefore understood that changes may be made inthe particular embodiments of the invention disclosed which are withinthe scope and spirit of the invention as outlined by the appendedclaims. Having thus described the invention with the details andparticularity required by the patent laws, what is claimed and desiredprotected by Letters Patent is set forth in the appended claims.

1. A method for forming a photochromically-enabled bifocal ophthalmiclens by incorporating a thermoplastic polyurethane (TPU) therein,comprising the steps of: injecting molten thermoplastic polycarbonate(PC) resin into an edge-gated cavity of an injection molding machinehaving a vertical equipment axis to provide a lens substrate; applyingan acrylate-based coating composition onto the lens substrate whichcures to form an imbibable bifocal surface; and imbibing a photochromicdye solution into the surface; wherein the acrylate-based compositioncontains an adhesion enhancer comprising a TPU so thatcoating-to-substrate integrity is maintained following said imbibingstep.
 2. The method of claim 1, wherein said injecting step comprisesproviding a single vision (SV) lens substrate, and said applying stepcomprises overmolding.
 3. The method of claim 1, wherein said injectingstep comprises providing a bifocal lens substrate.
 4. The method ofclaim 1, wherein said applying step comprises: depositing anunpressurized full metered charge of the composition on to theupwardly-facing convex surface of the lens substrate; and clamping downan upper mold half to form a bifocal lens cavity.
 5. The method of claim1, wherein the coating composition comprises at least 90% by weight of ablend of acrylate-based thermoset materials, and less than 5 phm TPUparts per hundred parts of monomer (phm).
 6. The method of claim 5,wherein the coating composition is devoid of dyes which are selectedfrom regular dyes, photochromic dyes, dichroic dyes and a combinationthereof.
 7. The method of claim 5, wherein the coating compositioncomprises less than about 2 TPU phm, wherein the TPU is apolycarbonate-based TPU.
 8. The method of claim 5, wherein the TPU is analiphatic polycarbonate-based TPU.
 9. The method of claim 5, wherein thephotochromically-enabled bifocal ophthalmic lens has an % T initialabove about
 80. 10. The method of claim 5, wherein thephotochromically-enabled bifocal ophthalmic lens has a % T dark around20.
 11. The method of claim 1, wherein said applying step comprises:formulating the coating composition by dissolving a metal salt and theTPU in a solvent blend comprising: (1) a monofunctional (meth)acrylate;(2) a multifunctional (meth)acrylate; (3) a difunctional (meth)acrylate;(4) an aliphatic urethane diacrylate; and adding an initiator.
 12. Themethod of claim 1, wherein said applying step comprises: formulating thecoating composition by dissolving a metal salt, a dye, and the TPU in asolvent blend comprising: (1) a monofunctional (meth)acrylate; (2) amultifunctional (meth)acrylate; (3) a difunctional (meth)acrylate; (4)an aliphatic urethane diacrylate; and adding an initiator.
 13. Themethod of claim 12, wherein said dye is selected from regular dye,photochromic dye, dichroic dye and a combination thereof.
 14. Athermoset composition comprising: (1) at least one monofunctional(meth)acrylate; (2) at least one multifunctional (meth)acrylate; (3) atleast one difunctional (meth)acrylate; (4) at least one aliphaticurethane diacrylate; (5) at least one metal salt; (6) at least oneinitiator; and (7) at least one thermoplastic polyurethane (TPU).
 15. Athermoset composition of claim 14, further comprising at least one dyeselected from regular dye, photochromic dye, dichroic dye and acombination thereof.
 16. The composition of claim 14, wherein themonofunctional (meth)acrylate is selected from the group consisting ofisobornyl acrylate, methyl methacrylate, benzyl methacrylate, benzylacrylate hydroxypropyl methacrylate, 2-phenoxyethyl methacrylate, andcombinations thereof.
 17. The composition of claim 16, wherein themonofunctional (meth)acrylate is benzyl acrylate.
 18. The composition ofclaim 14, wherein the multifunctional (meth)acrylate is selected fromthe group consisting of dipentaerythritol hexaacrylate,dipentaerythritol pentaacrylate, hexafunctional aliphatic urethaneacrylate, and combinations thereof.
 19. The composition of claim 18,wherein the multifunctional (meth)acrylate is dipentaerythitolpentaacrylate.
 20. The composition of claim 14, wherein the difunctional(meth)acrylate is selected from the group consisting of 1,6-hexanedioldiacrylate, ethoxylated bisphenol A di(meth)acrylate, polyethyleneglycol di(meth)acrylate and combinations thereof.
 21. The composition ofclaim 14, wherein the metal salt includes cobalt naphthenate.
 22. Thecomposition of claim 14, wherein the initiator istert-butylperoxybenzoate.
 23. The composition of claim 14, wherein thethermoplastic polyurethane comprises a polycarbonate-based aliphaticpolyurethane having a Specific gravity of between 1.0 and 1.3; aFlexural modulus between 550 and of 690 psi; an Ultimate Tensile ofbetween 4,000 and 6,000 psi; and Mold shrinkage of 0.006-0.014 in/in.24. The composition of claim 14, further comprising: (1) said at leastone monofunctional (meth)acrylate being present in an amount from 5% to40% by weight; (2) said at least one multifunctional (meth)acrylatebeing present in an amount from 5% to 50% by weight; (3) saiddifunctional (meth)acrylate being present in an amount from 5% to 50% byweight; (4) said aliphatic urethane diacrylate being present in anamount from 5% to 60% by weight; (5) said at least one metal salt beingpresent in an amount from 0.05 to 2.0 phm; (6) said at least oneinitiator being present in an amount from 0.1 to 5.0 phm; and (7) saidat least one thermoplastic polyurethane (TPU) being present in an amountfrom 0.5 phm to 5.0 phm.
 25. The composition of claim 15, furthercomprising said at least one dye being present in an amount comprisedfrom 0.1% to 5.0% by weight.
 26. The composition of claim 14, furthercomprising: (1) said at least one monofunctional (meth)acrylate beingpresent in an amount from 10 to 20% by weight; (2) said at least onemultifunctional (meth)acrylate being present in an amount from 10 to 35%by weight; (3) said difunctional (meth)acrylate being present in anamount from 10% to 35% by weight; and (4) said aliphatic urethanediacrylate being present in an amount from 30% to 50% by weight.
 27. Thecomposition of claim 14, further comprising: said at least one metalsalt being present in an amount of 0.25 phm; and said at least oneinitiator being present in an amount of 1.5 phm.
 28. The composition ofclaim 14, further comprising: said at least one thermoplasticpolyurethane (TPU) being present in an amount of about 1.0 phm.